3500 TERMINAL AVE Geotech Report 2022-10-25

Port of Everett—South Terminal Wharf& Electrical Upgrades—Phase 2 119 Existing Piles We understand that the terminal is currently supported on 18-and 24-inch-diameter,hollow and solid, octagonal, prestressed concrete piles.These piles were generally installed in seven or eight rows(labeled A to H)except where piles were shifted or added during construction. Occasional battered piles are installed between Rows G and H along the top of slope.The as-built sizes and depths of the piles are shown on the historical plan in Attachment 3. Piles,if cut off,were cast directly in a cast-in-place concrete pile cap with extended strands or dowel bars extended into the pile caps,or were extended with an additional concrete section to reach the bottom of cap. Based on the 2009 South Terminal Condition Assessment,the existing piles are generally in a serviceable condition,except for localized vertical cracks and spalls(Port of Everett 2010).We understand that minor repairs on these piles may be necessary,but pile replacement is not expected. Recent Pile Driving at the Site The recent pile driving activities in the north end of the site consisted of installing 28 18-inch-diameter and 14 24-inch-diameter steel pipe piles.The pile installation was observed by Shannon and Wilson and the, pile driving logs along with daily field reports are in the Moffat and Nichol review memorandum in Attachment 4.The piles were generally vibrated through the upper 40 to 50 feet below mudline and then driven the final 10 to 20 feet with a single-acting diesel hammer. Restrikes were performed on 29 piles (69 percent). Dynamic testing was performed using a pile driving analyzer(PDA)and analyzed in Case Pile Wave Analysis Program (CAPWAP)on 5 production piles(12 percent)and the results are in Attachment 5. Based on the analyses completed by Shannon and Wilson,these piles were installed with a factor of safety of 1.5,which does not meet the minimum requirements of the building code for compressive axial capacity of driven piles for static loading. Static Analysis For static loading,vertical compressive loads at the pile head can be resisted by friction along the pile sides (shaft)and by end bearing at the tip. Because the bearing layer is variable,required pile lengths can only be approximated based on field boring logs available at discrete locations.The main purpose of our static analysis is to provide the basis for estimating pile quantities.Actual pile embedment lengths will depend on driving resistance and other factors, and may need to be adjusted in the field depending on the results of monitoring during installations. We used the API RP 2A method in APILE v.2015 and the CAPWAP results from recent pile driving to calibrate the analysis soil properties and predict the vertical pile capacity for various pile types. Generalized subsurface profile D-D' (Figure 6)was used to determine the soil profile for three groups of rows(A to C, D to E,and F to H). Pile capacity charts were developed for close-ended steel pipe piles as well as octagonal precast concrete piles at diameters of 18 inches and 24 inches.We understand that the recent pipe piles were driven with a conical steel tip welded to the end of the pile and assume that similar tips will be used with new piles.Any end bearing plates should be designed such that the length would be susceptible to failure prior to the bearing plate.The charts are shown on Figures 13 through 27. Note that AN 19232-01 HARTCROWSER December 6,2017